1. Field of the Invention
This invention relates to a pulse waveform generator for controlling of pulse waveform output of a microcomputer, more particularly to a pulse-width-modulation (PWM) waveform generator the output level of which can be selected in every PWM waveform output cycle.
2. Description of the Background Art
PWM waveform generators used in microcomputers have generally produced waveforms in which every cycle of the PWM waveform output starts from the same level, or at least the starting level cannot be changed during PWM waveform output. This considerably restricts the types of waveforms that can be obtained, and limits the usefulness of the PWM waveform generator.